1. Field of the Invention
The invention relates to a vehicle seat with an inherently stable backrest formed of plastic.
2. Description of the Background Art
Seat structures in vehicles are required to meet specific safety standards. These safety standards are higher for front seats in motor vehicles than for their back seats, because the front seats must absorb in addition the impact of the body and head of the back seat passengers. Therefore, most front seat backs are metal constructions, although other materials, particularly plastics or plastic composites with a high modulus of elasticity (high rigidity), can also be used. Seats made of metal constructions are relatively heavy and expensive. Alternatives can be backrests or seat components that are made at least partially of plastic or whose plastic is designed to be suitably stable or is at least partially reinforced.
DE 94 06 437 U1 discloses a vehicle seat with a backrest and a lower seat component, whose backrest is formed as an integrally formed hollow body, whereby the backrest is made of a plastic, particularly a thermoplastic resin. A reinforcing member made of a material with a high modulus of elasticity is incorporated into the plastic body of the backrest.
DE 22 23 361 discloses a frame for a vehicle seat, which is characterized by a reinforcing part embedded in a plastic body and made of wire, tubular metal, or pressed metal.
Methods such as compression molding, extrusion, and injection molding are known for producing molded plastic parts.
Injection molding, or the injection molding process, is a shaping method which is used very often in plastics processing. Directly usable molded parts can be produced extremely economically in large numbers by the injection molding process. Described in simplified form, the method works as follows: In an injection molding machine which has a heatable container with a discharging device, the particular thermoplastic plastic is melted with application of heat, and injected into a metal form, which is generally called a die. The cavity of the die determines the outer form and the surface structure of the part to be manufactured.